Vehicle seats having a built in protective system to protect the passenger positioned in the vehicle seat have been in development for several years. Whiplash, or whiplash associated disorder (WAD), is a term describing a range of injuries and symptoms which are common among injured passengers in vehicle accidents. It is common that WADs occur as a result of an object colliding into the rear of the vehicle, i.e. a rear collision, and in these circumstances they are also referred to as cervical acceleration-deceleration injuries. During a sudden acceleration from a colliding object having a velocity as low as about 6-8 km/h, a passenger's sensitive neck is subjected to a weight 4-5 times the normal weight. The sudden increase can force the spine to adopt an unfavorable form which in the end stretches or extends the spine. Patients having WAD usually tend not to have any visible injuries to the ligaments, discs, muscles or joints which makes the treatment difficult. It can be very difficult and painful for patients having WAD, while at the same time WAD imparts high costs to society in the form of health care and rehabilitation system costs.
One factor which affects the risk of acquiring WAD is how the vehicle seat is positioned, i.e. the position of the seat, back rest and head rest. Different car manufacturers have approached this problem differently: some use an active head restraint, while some use a system commonly referred to as WHIPS, or whiplash protection/prevention system.
In the publication of WO 00/53452 A1 to Autoliv A B, a seat carrier is disclosed. The seat carrier comprises a kinetic energy absorber. In case of a rear impact, the seat carrier is adapted to pivot and the kinetic energy absorber is intended to absorb some of the forces imparted to the sear carrier due to a collision. The kinetic energy absorber is arranged on a support structure beneath the seat and is very space consuming and requires a high number of individual components to operate properly.